The present invention relates to a recording and reproducing device for a video signal, and more particularly to a device capable of reducing noise components in a recording or reproducing system of, e.g., VTR.
In the reproducing system of the conventional recording and reproducing device for video signal, various de-emphasis circuits have been devised in order to reduce noises included in a reproduced video signal. As an example of conventional de-emphasis circuits, a circuit comprising a high-pass filter, a limiter, a coefficient multiplier, and a subtracter which are connected in series is proposed. According to this circuit, a reproduced video signal undergoes amplitude limitation by the limiter after subjected to filtering by the high-pass filter. After the signal thus processed is multiplied by a predetermined coefficient by the coefficient multiplier, it is subtracted from the input reproduced video signal and then is output therefrom. As another example of conventional de-emphasis circuits, a circuit of the feedback type is also proposed. According to this circuit, a signal which has been multiplied by the coefficient multiplier is fed back to the high-pass filter as an input signal.
The reproduced video signal includes a random noise of no periodicity, and an impulse noise having an extremely short duration. The first-mentioned de-emphasis circuit can effectively reduce the impulse noise, but fails to effectively reduce the random noise. In contrast, the last-mentioned de-emphasis circuit of the feedback type can effectively reduce the random noise, but fails to effectively reduce the impulse noise.
As just described above, a circuit which can satisfactorily cope with both the random noise and the impulse noise has not been proposed in the art. The adverse effect, namely the random or the impulse noise becomes more conspicuous as the amount of the emphasis is intended to increase.